High-calorie, high-sodium choices are typically on the menu when parents purchase for their children. Why? Because both children and adults liked the food and the convenience.

The study of data compiled by researchers in the Department of Pediatrics at the University of California, San Diego, appearing this week in the new journal Childhood Obesity, showed that convenience resulted in lunchtime meals that accounted for between 36 and 51 percent of a child's daily caloric needs. In addition, 35 to 39 percent of calories came from fat and the meals provided more than 50 percent of the recommended total daily sodium intake for most children- and as high as 100 percent of sodium levels recommended for pre-schoolers.

"We found that families perceived fast-food restaurants as easy and cheap, and many were using fast food as a reward for their children," said Kerri N. Boutelle, PhD, Behavioral Director of the Weight and Wellness Clinic at the University of California, San Diego and Rady Children's Hospital-San Diego, who has studied childhood obesity, its causes and treatment for over 15 years. "Considering the high prevalence of fast-food consumptions by adults as well as kids, it's important to recognize the impact of fast food and its impact on the current obesity epidemic in the U.S."

The UC San Diego researchers surveyed 544 families with children entering a fast-food chain restaurant located inside Rady Children's Hospital in San Diego, California at lunch time over a six-week period. Families were asked to retain and present their receipts from food purchases and complete a brief survey. Families were provided a $2 incentive to participate.

Families were asked to clarify their purchases: for whom each item was purchased, if items were shared, sizes of individual items (small, medium, large), whether soft drinks were regular or diet, what items were included in any combination meals purchased, and if there were any modifications to their order. For every purchased item, the surveyors asked for age and gender of the person eating it.

"The number of meals and snacks eaten away from home is believed to contribute to excess calories consumed by children, and this number has increased dramatically in the past 30 years," said Boutelle. "On a typical day, a remarkable 30 percent of youth report consuming fast food."

The purpose of the study was to evaluate the nutritional content and quality of food, as well as the reasons reported for dining at a fast-food restaurant. Perhaps unsurprisingly, the top reasons for going to this restaurant were "the children like the food" and it was "convenient." Just over half the families reported the choice as "a reward for visiting the hospital" (about the same number as replied "hungry with no other options").

But adults also overwhelmingly reported that they liked the food. The toys included with the children's meals did not appear to be a top reason (49 percent said it didn't enter into their decision "at all").

The nutritional content of the food choices supported other published data on fast-food and dietary intake on children. The highest percentage of daily caloric needs represented by these meals (51 percent) was in the age 2 to 5 years. Menu items most frequently purchased for preschoolers were French fries, soda, chicken nuggets, cheeseburgers and hamburgers. Meals for older children years were similar, with the addition of hot apple pies (ages 6 to 11) and chocolate chip cookies (ages 12 to 18).

Of note, soda was purchased much more often than milk or juice when a drink was purchased. The researchers also observed that while healthier options such as apple dippers or fruit parfaits were available, families did not seem to choose them over more typical fast foods.

Strengths of this study were that purchase receipts were an objective measure of meal choices, and a large number of families -- both economically and ethnically diverse -- was polled. However, limitations included the lack of data on what was actually consumed, and that the study may have been influenced by the restaurant's location inside a children's hospital, limiting the choice of restaurants if not the food choices themselves.

"Bottom line, we need to educate families on making health decisions when in a fast-food restaurant," said Boutelle, acknowledging that any intervention to decrease fast-food consumption will need to take into account that people of all ages simply like fast food.